Transition

Transitions are depicted with directed arcs and they provide means to move tokens from one place to another. The following property window is displayed if pointer tool is selected from the palette and is double-clicked (see figure)

• Name is a user assigned identifier that does not have to be unique.
• Details on Labels and indeces are provided here Labels and Indeces in APN
• Aging can be either true or false. This property controlled from Place property dialog
• Age renewal factor: a multiplier between 0 and 1 that applied to the token's age upon firing: 1 (default value) implies that age did not change, 0 implies that it was reset to zero.
• Different firing policies can be specified for different colors by selecting a color ID: new policies can be added using button "Add policy". Current policy can be removed by pressing "Remove policy" button.
• "Color change factor is defined separately for each color policy and it allows to change the color by a specified increment (an integer that can be either negative or positive).
• In the present version, one of the following types of transitions can be specified:
• none (no firing occurs, useful to "filtering" tokens based on their color)
• fixed delay (deterministic positive value, can be used to model immediate transitions if conflict resolution is based on priorities: smaller positive delay corresponds to higher priority)
• two-parameter Weibull distribution (scale and shape parameters are specified)
• log-normal (two parameters). The first parameter (lognormal mean) is what is commonly referred to as μ, and the second parameter (lognormal variances) corresponds to σ²
• uniform (one parameter for the upper limit, with the lower limit being zero)
• inverse fixed (this is useful for "rejuvinating" tokens: transition fires when the age is zero, and the ages of tokens in the input place are continiously reduced when this transition is designated as aging).
• exponential (constant rate): only one paramater is specified
• fixed, aged-dependent: total delay is equal to the provided scale multiplied by the initial age when the token is enabled
• triangular symmetric transition (min and max are specified)
• The dialog permits specification of the appropriate parameters for each type of distribution.



Transition menu when the property is defined globally

• Pressing OK button dismisses the dialog and sets parameters as they appear in the dialog. Pressing "Confirm" sets parameters that were input by the user without dismissing the dialog. Please note that, unless one of these two buttons are pressed, the changes input my the user will not be remembered (e.g., if one selects to look at a firing policy for another color)
• Change of color integer is only allowed when it does not violate the existing color ordering.
• The firing policies are interpolated to the left: they extend for all the colors that are less or equal to the given one (and extend in the opposite direction ONLY if there are no policies with the larger values are defined). Example: if we have two policies defined for colors 2 and 4, then the first policy will be valid for colors 0, 1,2 and the second policy will work for colors 3,4 and larger. If we introduce an additional policy for color 0, then it will apply for color 0 only.
• Instead of specifying a local parameter, linked transition box can be checked (for each color policy separately) and then transiton is linked to a global control parameter as shown to the right
• Global transition parameters must be defined first to be linked, as decrribed in global control parameter